Drive controller for stepping motor

Abstract

A drive controller of the N-phase stepping motor includes a signal generator for generating M pulse signals at such an interval that the stepping motor can be driven in response to the pulse signals so as to rotate the stepping motor through an M step angle in one direction, and a driver for determining an exciting phase which is one step ahead of the current exciting phase as a next exciting phase in response to the pulse signal generated from the signal generator and exciting the stepping motor set in the thus determined exciting phase. In the drive controller, the signal generator generates pulse signals as a pulse signal group at such an interval that the stepping motor cannot respond to the pulse signals and repeatedly generates the pulse signal group by M times at such an interval that the stepping motor can be driven in response thereto so as to rotate the stepping motor in a reverse direction.

What is claimed is: 
     
       1. A drive controller for an N-phase stepping motor, comprising: signal generating means for generating a pulse sequence including M pulses to rotate the stepping motor through M step angles in one direction, and for generating a pulse sequence including M groups of (N-1) pulses to rotate the stepping motor through M step angles in a reverse direction, said M pulses being separated by a variable excitation interval set within a range in which the stepping motor is responsive, said (N-1) pulses being separated by a fixed excitation interval set within a range in which the stepping motor is not responsive, and said M pulse groups being separated by the variable excitation interval; and   drive means coupled to said signal generating means for exciting the stepping motor, wherein the exciting phase of said stepping motor is advanced by one step in response to a pulse generated from said signal generating means.   
     
     
       2. The drive controller of claim 1, wherein said signal generating means has a single output terminal for the pulse sequence generated to rotate said stepping motor in either said one or said reverse direction. 
     
     
       3. The drive controller of claim 2, wherein said driver means includes counter means for specifying two phases of said N-phase stepping motor, in response to the pulse supplied from the single output terminal of said signal generating means. 
     
     
       4. The drive controller of claim 3, wherein: said stepping motor includes first, second, third and fourth exciting coils:   said counter means includes first and second D-type flip-flops each having a D input terminal, a clock terminal, a Q output terminal and a Q output terminal;   each clock terminal of the first and second flip-flops is coupled to the single output terminal of said signal generating means;   the D input terminal of said first flip-flop is connected to the Q output terminal of said second flip-flop;   the D input terminal of said second flip flow is connected to the Q output terminal of said first flip-flop; and   the Q output terminal of said first flip-flop, the Q output terminal of said second flip-flop, and the e,ovs/Q/  output terminal of said first flip-flop, and the e,ovs/Q/  output terminal of said second flip-flop are connected respectively to the first, second, third and fourth exciting coils of said stepping motor.   
     
     
       5. The drive controller of claim 1, wherein said signal generating means includes changing means for changing the variable excitation interval to accelerate and decelerate a rotation speed of said stepping motor. 
     
     
       6. The drive controller of claim 5, wherein said changing means includes means for decreasing the variable excitation interval during a first preset period, for maintaining the variable excitation interval during a second preset period subsequent to the first preset period, and for increasing the variable excitation interval during the third preset period subsequent to the second preset period.